I have this combination and have been having the same issue (although I was able to get it tight enough to be usable).

Still, I am happy because this is probably the burliest clip/strap combination out there. If you've ever busted a strap going downhill you know what I am talking about.

I've toyed with the idea of shaving off a little of the fat part leading up to the non-buckle side. If the buckles can get lower, they won't run up against the eyelet and you should be able to get it tighter.